A Church History Series: The Early Church – An Overview

How Christianity Took Root, Spread, and Defined Itself (AD 30–325)

When people today speak about “returning to the early church,” they often imagine a loose, leaderless, doctrine-light movement. But the actual history of the early Church — from the ministry of Jesus (c. AD 30) to the First Council of Nicaea in 325 — tells a very different story.

The first three centuries of Christianity were marked by explosive growth, fierce persecution, intense theological clarification, and the establishment of the Church’s structure, sacraments, and authority.

Understanding this era is the foundation upon which the entire Christian faith rests.

The Apostolic Age (c. AD 30–100): The Church Is Born

Everything begins in Jerusalem.

Following Jesus’ crucifixion and resurrection, He appears to His disciples, breathes on them, and says, “Receive the Holy Spirit” (John 20:22). This moment echoes the breath of God into Adam — a new creation, a new humanity, a newly empowered people of God.

Pentecost launches the Church publicly, and the apostles begin the mission Christ commanded.

Key developments in this earliest era include:

• The leadership of Peter, John, and James in the Jerusalem church.

• Paul’s conversion and missionary journeys across the Roman world.

• Andrew embarked on extensive missionary travels across Asia Minor, Greece, and Macedonia

• The Council of Jerusalem (c. AD 48–50) affirming that Gentile converts did not need to follow the entire Mosaic Law.

• The formation of local churches led by bishops, presbyters (priests), and deacons — the new covenantal priesthood serving under Christ.

  
  

By the end of the first century, Christianity had reached major cities throughout the empire.

A Church Under Fire: Persecution and Perseverance

While the Church grew, it did so under intense pressure. Roman persecution ranged from localized hostility to empire-wide crackdowns.

Notable persecutions included:

• Nero (AD 64): Christians falsely blamed for the Great Fire of Rome.

• Decius (249–251) and Diocletian (303): Demands to renounce Christ or face torture, imprisonment, or death.

Yet the Church thrived.

Why did Christianity spread under persecution?

• A message of salvation and eternal life

• Moral and spiritual stability

• Radical charity: care for the sick, poor, widows, and orphans

The blood of the martyrs became the seed of the Church.

The Turning Point: Constantine and the Edict of Milan (AD 313)

Everything changes when Emperor Constantine converts to Christianity.

The Edict of Milan (313) grants full legal freedom to Christians, ending centuries of persecution. Suddenly:

• Bishops could meet publicly

• Internal disputes could be addressed

• Churches could be built

• Evangelism expanded freely

By AD 380, Nicene Christianity becomes the official religion of the Roman Empire under Theodosius I.

The persecuted minority becomes the majority.

Theological Development and the Fight for Orthodoxy

The early Church was not vague or doctrinally loose. Instead, it wrestled deeply with Christological and Trinitarian truth.

Major heresies the Church confronted:

• Gnosticism — salvation through secret knowledge; denial of Christ’s true humanity

• Docetism — Christ only appeared human

• Arianism — denial of Christ’s full divinity

Key defenders of the faith included:

• Justin Martyr

• Irenaeus of Lyons

• Tertullian

• Origen

They appealed to Scripture and apostolic tradition passed down through bishops.

The First Council of Nicaea (AD 325)

Convened by Constantine, this first ecumenical council produced the Nicene Creed, affirming:

• Christ is “God from God, Light from Light, true God from true God.”

• Christ is homoousios with the Father — of the same divine substance.

• The apostolic faith is the Church’s faith.

Nicaea becomes a defining moment, anchoring orthodoxy for all Christians.

How the New Testament Canon Formed

The early Church did not invent Scripture — it recognized the apostolic writings already used throughout the Christian world.

• Athanasius’s Festal Letter (367) lists the 27 NT books we have today.

• Council of Carthage later ratifies the same list.

The same Church that wrote the New Testament is the Church that preserved and canonized it.

The Apostolic Foundation of the Church

A single theme underlies all early Christian history: apostolic authority.

Jesus gave real authority to real leaders:

• “Receive the Holy Spirit.” (John 20:22)

• “Whatever you bind… whatever you loose…” (Matt. 18:18)

• “I will give you the keys of the kingdom…” (Matt. 16:19)

Peter, Paul, James, John, and Andrew became pillars of the early Christians. From them came bishops who:

• Continued Christ’s mission

• Preserved His teachings

• Guarded unity

• Passed down authority

The early Christian test for authenticity was simple:

Trace the line of apostolic succession.

Denominations formed nearly two millennia later with no connection to the apostles would not have been recognized by the early Church.

Why Early Church History Matters Today

Modern Christians often treat Christianity like a buffet line, where they can pick and choose what they want to take, or leave, from the original orthodox interpretations, traditions, and practices. The early Church reveals a different reality.

The early Church was:

• One in faith

• Holy in calling

• Catholic (universal) in scope

• Apostolic in structure and doctrine

This is:

• The Church Christ founded

• The Church the apostles built

• The Church the martyrs died for

• The Church the Fathers defended

Every Christian tradition today stands on the foundation laid in the first 300 years.

To understand Christianity, you must understand the early Church.